/*
 * Tencent is pleased to support the open source community by making BK-CI 蓝鲸持续集成平台 available.
 *
 * Copyright (C) 2020 THL A29 Limited, a Tencent company.  All rights reserved.
 *
 * BK-CI 蓝鲸持续集成平台 is licensed under the MIT license.
 *
 * A copy of the MIT License is included in this file.
 *
 *
 * Terms of the MIT License:
 * ---------------------------------------------------
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

package com.tencent.bkrepo.common.storage.filesystem

import com.tencent.bkrepo.common.artifact.stream.closeQuietly
import com.tencent.bkrepo.common.artifact.stream.releaseQuietly
import java.io.File
import java.io.InputStream
import java.io.RandomAccessFile
import java.nio.channels.Channels
import java.nio.channels.FileChannel
import java.nio.channels.FileLock
import java.nio.channels.OverlappingFileLockException
import java.nio.channels.ReadableByteChannel

object FileLockExecutor {

    private const val READ_WRITE = "rw"

    /**
     * 独占锁，只能单独写，不能读
     */
    fun executeInLock(file: File, shared: Boolean = false, block: (channel: FileChannel) -> Unit) {
        RandomAccessFile(file, READ_WRITE).use {
            val channel = it.channel
            val lock = acquireLock(channel, shared)
            try {
                block(channel)
            } catch (ignored: RuntimeException) {
                throw ignored
            } finally {
                releaseLock(lock)
            }
        }
    }

    /**
     * 共享锁, 支持多读，不能写
     */
    fun executeInLock(inputStream: InputStream, block: (channel: ReadableByteChannel) -> Unit) {
        Channels.newChannel(inputStream).use {
            if (it is FileChannel) {
                val lock = acquireLock(it, true)
                try {
                    block(it)
                } catch (ignored: RuntimeException) {
                    throw ignored
                } finally {
                    releaseLock(lock)
                }
            } else {
                block(it)
            }
        }
    }

    private fun acquireLock(channel: FileChannel, shared: Boolean): FileLock {
        while (true) {
            try {
                channel.tryLock(0L, Long.MAX_VALUE, shared)?.let { return it }
                Thread.sleep(200)
            } catch (ignored: OverlappingFileLockException) {
                // locked by the same JVM, ignore
            }
        }
    }

    private fun releaseLock(lock: FileLock) {
        lock.releaseQuietly()
        lock.channel().closeQuietly()
    }
}
